Electrical glow-light



W. NERNST.

ELECTRICAL GLOW LIGHT.

(Application lsd 9ct. 2, 1697.)

No.' 623,8". Patented Apr. 25, |899.

(No Modell.)

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\VALTHER NERNST, OF GTTINGEN, GERMANY, ASSIGNOR TO GEORGE VESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

ELECTRICAL GLOW-LIGHT.

SPECIFICATION forming part of Letters Patent No. 623,811, dated April 25, 1899.

Application filed October 2, 1897. SerialNO. 653,849, (No model.)

To @ZZ whom t may concern:

Be it known that I, WALTHER NnRNs'r, a

subject of the German Emperor, and a resident of Gttingen, Germany, have invented certain new and useful Improvement-s in Electrical Glow-Lights, of which the following is a specification.

My invention while it relates generally to the class of electric-lighting apparatus in which conducting materials are heated to ,incandesence by the passage ofv electric currents differs therefrom in many important respects.

The incandescent electric lamps which have heretofore been used commercially comprise an attenuated iilament of carbon inclosed in a chamber from which the air has been exhausted. Numerous attempts have been made to produce a filament for an incandescent lamp which could be used in.y the open air, but thus far without any practical success. It has been found necessary to inclose all these materials in chambers freed from oxygen; otherwise they are rapidly consumed. They, moreover, have the capacity of emitting in the form of. light only a smallporltion of the electrical energy consumed in 'maintaining them in an incandescent condition. I have found that certain of the dry conductors of the second class or dry electrolytes-that is to say, materials which when in a conducting condition conduct current by electrolytic action-will when heated to an incandescence under suitable conditions become sufficiently conducting under moderate electrical pressures to permit the passage. of sufficient electric current to maintain them' in such heated conducting state and that the light given off thereby may be much greater per unit of electrical energy than is secured from electric conductors of the first class. It is, for example, possible to bring such substances as lime, magnesia, zirconia, and other of the rare earths, which are examples of dry electrolytes, to a conducting condition by the application of external heat-such, for instance, as may be obtained from an alcohollamp or a gas-flame-and if traversed by an electric current while in such heated condition they will be brought to an intense White heat and maintained in that condition by the passage ofthe current. They, moreover, have the capacity of withstanding these very high temperatu res even While exposed to the open air, so that exhausted receptacles or those filled with poorly-conducting gases are not necessary, although permissible,with my invention. I have, for example, by external means heated in the open air a small hollow cylinder of burnt magnesia of seven millimeters length and l. 5 millimeters thickness to a conducting temperature and with a current of less than one-third of anv ampere at one hundred and eighteen volts pressure obtained a light much greater than that of the present commercial sixteen-candle-power incandescent lamp. V

My new form of lamp is capable of being operated by either alternating or continuous currents; but the former have for some purposes beenfound more desirable, as usually the lamp will endure longer under the iniiuence of an alternating than of a continuous current.

Inasmuch as the materials referred to are essentially insulators at ordinary temperatures, it is necessary that theybe brought to a comparatively high temperature before they will begin to act as conductors; but when they are brought to a conducting condition and current is permitted to traverse them their temperature and incandescence is still further increased and their resistance low'- ered. The external heat may be withdrawn when the light-giving bodyhas itself become sufficiently conducting to convey the current; but in some cases it may be desirable to continue the external heat also.

In the German patent of Jablochkoff, No. 1,630, there is suggested the possibility of heating a kaolin strip or plate placed between two conductors by means of the electricI spark` thereof, and my form of lamp permits the use of currents of much lower pressure. It has also been proposed (United States Patent No. 322,033) to heat a small section of the length of a strip of refractory material by cont-act with the tip of a carbon pencil heated by the passage of an electric current and as the peucil dissipates establish a current through it and the heatedsection of the refractory strip; but this form of construction differs from mine, among other things, in being much more complicated and uncertain in its results and iu being dependent upon the shifting of a movable contact between the heating-body and the illnminant, which involves an irregular and imperfect contact and undue resistance and diminishes the economy and durability of the lamp, and, moreover, the contact of the heated carbon with the heated strip will quickly reduce and disintegrate the latter.

The accom panying drawing illustrates one method of employing my invention.

ln the drawing, A represents a base carrying two binding-posts B l2. The bindingposts are resliiectivelyv designed to be connected with the conductors of asuitable electric circuit supplied with the desired pressure-say one hundred or two hundred volts.

k Greater or less electrical pressures may, however, be employed. Conductors S' and S2 are connected with thcrespective binding-posts l and B2. Between the conductors S S2 there is mounted the light-giving body C, which is here shown as consisting of a small bar, rod, or cylinder and is composed of such dry electrolyte or rare earth as hereinbefore described. The conductors S and S2 may be elastic, if desired, so as not to subject the body C to undue strains.

For the purpose of heating the light-giving bodyC to the proper temperature for rendering it conductive under the influence of the electrical pressure to which it is subjected the tlame of alamp C' maybe used. Any other suitable device may be employed for applying the initial external heat; but it should be noted that t'heinitial heat must be imparted by means separated from the body C, since any material placed in actual contact with the dry electrolyte C will either itself be decomposed or driven off by the intense heat developed when that body is traversed by an electric current or result in a reduction or disintegration of the electrolyte composing the lightgiving body.

I claim as my inventionl. An improved electrical incandescent lamp, consisting ot' a strip of material which is an insulator at ordinary temperatures and becomes a good conductor and luminant at high temperatures,co mbined at its extremities with fixed terminals for conducting current through the same, and with a heat-producing structure separate from the luminant and operating to raise all parts of the strip between the fixed terminals to a conducting temperature prior to the passage of theilluminatingcurrent substantially as described.

2. The method of producing light by the passage of an electric current through astrip of material which is a non-conductor at ordinary temperatures, but becomes a good conductor-and luminant at high temperatures which consists in heating the same through out, by a source of heat separated from the luminant, until it becomes a good conductor, and then maintaining its conductivity and luminosity bythe passage of an electric current, substantially as described.

An electric lamp consisting of a currentcarrying strip of material which is an insulator at ordinary temperatures and a relatively goed conductor at an incandescence temperature and heating apparatus separated therefrom and arran ged to heat the strip to a conducting` temperature throughout its entire section.

Signed at Berlin this 18th dayof September, 1897.

\VALTIIER NERNST.

Witnesses:

XV. HAUPT, LUDWIG Komet. 

